Process of removing carbon from metal pipes



.C0MP0SlTl0N i 2;)25 Cross Reference Oct. 9, 1923. 1,470,359

c. J. GREENSTREET PROCESS QR REMOVING CARBON FRO! METAL PIPES Filed April 17 1917 Q z fig //wmron ar g @nronzul Patented Oct. 9, 1923.

UNITED STATES PATENT OFF-ICE.

CHARLES J. GBEENSTREET, OF ST. LOUIS, MISSOURI, A SSIGNOR TO GASOLEFE COB,-

' PORATION, A CORPORATION OF DELAWARE.

PROCESS OI REMOVING CARBON FROM METAL PIPES.

Application filed April 1.7, 1917. Serial No. 162,608.

To all whom it may concern:

Beit known that I, CHARLES J. GREEN- STREET, a citizen of the United States, and

a resident of St. Louis, county of St, Louis,

State of Missouri, have invented certain new and useful Improvements 1n Processes for Removing Carbon from Metal Pipes, of

which the following is a specification.

The present invention relates to a-process of removing carbon from the interior of metal pipes such as those used in the treatment of petroleum oils in cracking processes or other similar uses.

When oil is heated under. pressure for the production of light hydrocarbons or is sub.-

jected to heat treatment for other purposes a hard cokelike deposit of carbon is usually formed on the inner surface of the apparatus employed and continues to increase as the treatment continues. lVhen the deposit has accumulated to such an extent as to interfere with the further operation of the process the treatment of the oil must be interrupted or stopped and the deposit of carbon removed by scraping or digging the 'coke from the surface of the apparatus or removed by other mechanical means.

The removal of carbon in this manner is particularly troublesome in tubular apparatus, in which the passages are very small, and'especially so in the case of the deposits which may be accidentally formed in the o ration of the Greenstreet process describe moval of carbon is provided in connection with this process.

In the normal operation of the Greenstreet process the oil is heated continuously in a long.pipe,'or coil of pipe, and the formation of carbon deposits is prevented by the ,presence of steam in the coil during treatment. Because of the avoidance of carbon deposits in the normal operation of the process it .is customary to construct the treating coils of a long continuous pipe extending back and forth entirely within a furnace and having no seams or joints by which the pipe may be separated into several'parts or otherwise opened for cleaning.

- It is therefore extremely difiicult to remove the carbon deposits which maybe accidentally formed at times, due to the carelessness of the operator, to a failure in the supply of,

F or drop in the pressure of, the steam which in Patent No. 1110924, since nor- -mally no provision for the mechanical reserves to prevent formation of carbon, to a temporary rise in temperature above that suitable for the operation of the process or to other accidental causes which are not present in the normal operation ofthe process but which occasionally occur in commercial operation.

An object of the present invention is to provide a rapid, inexpensive and eflicient process for removing carbon from the interior of metal pipes. I

Another object of the invention is to pro vide a process by which carbon deposits may In this drawing a supply tank 1 is connected with a pump 2 by means of the pipe 3. The pump discharges into a header 4. Connected with this header 4 area number of pipes 5, 6 and 7, each of which leads to cracking coil 8, 9 and 10, ince each of these units isa correspondin respectively.

exactl the same, a description of one will be en cient. In the pipe 5 is connected a meter 11 and valves 12 and 12. The'pipe 5 continues through the valve into the pipe 13 which leads into the furnace 14. The

pipe 13 is immediately connected with a preheating coil 15 which is placed in the coolest part of the furnace. The preheating coil is exactly the-same diameter as the corresponding cracking coil and, in fact, the cracking coil 8 is a continuation of preheating coil 15, the difference being merelyin the location of the coil and not in its con,- struction. A pipe 16 is also connected with the pipe 13 through a valve 17. A pipe 18 is likewise connected with the pipe 13 through valve 19. The pipe 5 supplies oil.

The pipe 16 supplies steam or other like gas, and the pipe 18 supplies air or other oxygen containing gas, the function of which gases will be hereinafter described.

[On the outer end of the cracking pipe is Cross placed a blow-ofi 20 containing a valve 21. The heating coil 8 is extended by means of the pipe 22 into an ex ansion drum 23. This pipe 22 is connecte to the expansion drum a suitable distance from the top thereof. The expansion drlun 23 has a pipe 24 leading therefrom through a valve 25 into the coil 26 of the condenser 26', which is shown in sectional plan view, The pipe 2% likewise connects with the expansion drum 23 a substantial distance above the bottom of the expansion drum. The expansion drum 23 has a pipe 27 connected near the bottom thereof through which any heavy residue, such as tar or other material, depending upon the nature of the oil being treated, may be drawn ofi therefrom through the valve 28 from time to time. Each of the expansion drums 23 has a pressure gage 40 connected with the upper portion thereof. At about the junction of the preheater and cracking pipe -is attached a pipe 44 with a valve 45. The pipe 44 leads t asource of steam or other gas. Likewise a pipe 46 is attached to the vapor linepipe 22 as it leaves the furnace and there is connected to the pipe 22 a pipe 48 near the expansion drum. The pipes 46 and 48 are connected with a source of steam or similar gas and ar provided to prevent the deposit of free'carbon in the pipe 22.

The hydrocarbon vapors and steam are conducted through the pipes 24 into the condenser coil which is cooled in any suitable manner, such as by immersion in water, and the condensed oil is conducted to a rundown tank 29 through the pipe 30. It sometimes happens that there are some uncondensed hydrocarbon vapors issuing throughthe pipe 30 into the run-down tank 29. These light vapors are conducted through the pipe 31 and vaive 32 into an absorption tower 33. This absorption tower 33- has a stream of naphtha, or other suitable material, running down therethrough from the tank 34 through the pipe 35 and valve 36. The product resulting from this mixture flows into the receiver 37 through pipe 38 controlled by valve 39.

I have shown only three coils in the furnace but in each of the plants which I have installed, I hav used six of these coils in each furnace. Only three were shown here as it simplifies the drawing to that extent.

The furnaces as usually constructed have a wall 43 separating the cracking coils. Each of the chambers in which the cracking coil is placed has some suitable means for heating itsomet-imes, an oil burner, and sometimes the chambers are'heated by coal. The particular means or method of heating forms no part of the present invention, and in view of the diagrammatic character of the illustration no means of heating the furnace has been shown.

Reference It sometimes happens, due to the carelessness ofthe operator, that a deposit of free carbon is found to exist in the cracking pipe or preheater or both. It is desirable to remove this carbon without the necessity of removing the coil from the furnace. This is accomplished by passin air, or other oxygen-containing gas, an steam, or similar gas, through the preheater and cracking pipes while the furnace is still heated. The carbon is attacked b the oxygen and the two combined and t e carbon is removed and passes off through the blow-off valve 21 which is fully open at this time. While I do not known exactly what takes'place, I venture the theory that the steam or similar gas so dilutes the oxygen, or cools the carbon', that the same is not heated to such a temperature as to melt the pipe. The carbon might be removed from the pipe by allowing air or other oxygen-containing gas to flow therethrough without steam or similar gas, provided care was taken to prevent the oxygen combining with the carbon at a suflicient rate to cause excessive local heat. In other words, the oxygen might be supplied intermittently, but I prefer to use air and steam which may be blown through continuously and which I have found in practice to be extremely efficacious in this part of the process.

- I have described my process in connection with hydrocarbon oil cracking apparatus but obviously the same is not limited in its use to such apparatus. It may be used in any case where carbon. is formed on the interior of a metal enclosure.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1, The process of removing carbon from pipes in an apparatus for converting hydrocarbons into other hydrocarbons havin a -difierent specific gravity and provided with pipes for conveying and converting the hydrocarbons, which consists in passing oxygen and steam simultaneously through the p1 e ect the oxidation of the carbon without melting the pipes.

2. The method of removing carbon from the interior of furnace pipes in an apparatus for converting hydrocarbons into other hydrocarbons having a different specific gravity and provided with pipes for conveying and converting the hydrocarbons, which consists in heat-mg said pipes, pass ing an oxygen containing gas into contact with the carbons for causing chemical reac tion therewith, and passing steam through said pipes while the chemical reaction in progressing to prevent the heat of "combustion exceeding temperatures injurious to the P P 3.. The'process of removing carbon from Hammer when heated in such proportion as to the interior walls of pipes in an apparatus passing steam through the pipes while the to for converting hydrocarbons into other hyoxidation is in progress, said steam being drocarbons having a different specific gravadapted to prevent the heat of combustion ity and provided with pipes for conveying exceeding temperatures injurious to the 5 and converting the hydrocarbons, which conpipes.

sists in heating said pipes exteriorly to a In testimony whereof, I have signed my 16 temperature at which oxidation of the carname to this specification. bon takes place, supplying oxygen within r y the pipes to combine with the carbon, and CHARLES J. GREENSTREET. 

